Extreme weather is becoming more frequent and more intense in many places because of climate change.
Scientists say this will continue whilst humans keep releasing planet-warming greenhouse gases.
Here are four ways climate change is linked to extreme weather.
1. Hotter, longer heatwaves
Even a small increase to average temperatures makes a big difference.
This is because the whole distribution of daily temperatures shifts to warmer levels, making hotter days more likely and more extreme.
Scientists use computer simulations to assess whether extreme weather events have been made more likely by warming caused by humans.
For example, the intense heatwaves that hit southern Europe and the southern US and Mexico in July 2023 would have been “virtually impossible” without human-caused climate change, according to the World Weather Attribution network (WWA).
But these events are no longer rare. If global warming reaches 2C above the pre-industrial period – before humans started burning fossil fuels at scale – these events are expected to happen every 2-5 years, the WWA warns.
In the UK, temperatures topped 40C for the first time on record in July 2022. This would have been “extremely unlikely” without climate change, the WWA says.
As well as happening more frequently, heatwaves are becoming longer and more intense in many places, including the UK, where 2022 was the warmest year on record.
This can happen as a result of “heat domes” – an area of high pressure where hot air is pushed down and trapped in place, causing temperatures to soar over large areas.
One theory suggests higher temperatures in the Arctic – which has warmed more than four times faster than the global average – are causing strong winds called the jet stream to slow, increasing the likelihood of heat domes.
2. Longer droughts
Linking climate change with specific individual droughts can be difficult. The availability of water depends on more than just temperature and rainfall.
But longer and more intense heatwaves can worsen droughts by drying out soils. This means the air above warms up more quickly, leading to more intense heat.
Increased demand for water from humans and farmers in hot weather puts even more stress on the water supply.
In parts of East Africa, there were five failed rainy seasons in a row between 2020 and 2022, as the region suffered its worst drought for 40 years.
Climate change has made droughts like this at least 100 times more likely, according to the WWA.
3. More fuel for wildfires
Fires happen naturally in many parts of the world. It’s difficult to know if climate change has caused a specific wildfire to spread because other factors are also relevant, like changes to the way land is used.
But climate change is making the “fire weather” conditions needed for their spread more likely, according to the UN’s climate body, the IPCC.
Extreme and long-lasting heat draws more and more moisture out of the ground and vegetation.
These tinder-dry conditions provide fuel for fires, which can spread at an incredible speed, particularly if winds are strong.
Canada is experiencing its worst wildfire season on record, with over 160,000 sq km (40 million acres) already burnt.
Climate change more than doubled the likelihood of the extreme “fire weather” conditions in eastern Canada that allowed the fires to spread, according to the WWA.
There have also been severe wildfires in Greece, Chile and Australia in 2023.
Global fire trends are complicated because of changing land use, but many regions have seen increases in the area burnt by extreme wildfires in recent decades, including the western US and Canada.
Wildfires are projected to become more frequent and intense in future globally due to the the combined effects of land use and climate change, according to a recent report by the UN Environment Programme.
It suggested that the number of the most extreme fires may increase by up to 50% by 2100.
4. More extreme rain
For every 1C rise in average temperature, the atmosphere can hold about 7% more moisture.
This can result in more droplets and heavier rainfall, sometimes in a shorter space of time and over a smaller area.
In 2022, Pakistan experienced its wettest July and August on record, triggering devastating floods affecting more than 33 million people. It is “likely” that climate change played a role, according to the WWA, but natural weather patterns like the monsoon may have been involved too.
Not all extreme rainfall events can be attributed to climate change, as other factors like natural variability or changes to land use can play a role. For example, climate change had a “limited” role in the heavy rainfall that hit the Emilia-Romagna region in northern Italy in May 2023, the WWA says.
But globally, the frequency and intensity of heavy rainfall events has increased over most land regions due to human activity, according to the IPCC.
And heavy precipitation will generally become more frequent and intense with further warming, the IPCC says.